There is a pressing need for basic research understanding the underlying individual- and community-level processes among American Indians. To this end, the proposed project will have three overarching Specific Aims. 1) To understand the behavioral epidemiology of HIV/AIDS and STDs in 2 American Indian tribes. 1.1) To provide a general description of HIV/AIDS knowledge attitudes, and perceived risk among American Indian populations both locally and nationally. 1.2) Using data from a sample of young adults (who are already participating in a longitudinal study about psychosocial aspects surrounding reproductive decisions in these 2 communities) to statistically model 3 individual-level behavioral theories, adopted to be culturally relevant for these communities. 1.3) To define sexual and other risk-taking behavior, define health-care seeking and access to care for STDS, and measure prevalence and history of STDs. 2) To describe the biomedical epidemiology Of HIV/AIDS and measure in 2 American Indian tribes. 2.1) To gather and synthesize data on incidence and prevalence of HIV/AIDS and other STDs in American Indian populations. 2.2) To use the STDSIM modeling to explore potential impact of various preventive interventions to reduce HIV transmission. 3) To use information gained from the behavioral and biomedical epidemiological investigations to select and design individual- and community-level preventive interventions. 3.1) Using ethnographic methods, to describe rural social networks and the experience of tribal and other practitioners both to identify culturally appropriate and community-specific points of intervention. 3.2) To describe current HIV/AIDS prevention programs and services available in these communities. 3.3) To work with community collaborators to select, design, and propose culturally appropriate preventive interventions tailored to individual and community needs. Researchers at the National Center for American Indian and Alaska Native Mental Health Research (NCAIANMHR) have forged a collaboration with the Center for AIDS and STD Research (CFAR) at the University of Washington to conduct this research. Together with the Indian communities that are already collaborating with us in the on-going projects utilized here, this partnership represents a powerful team to begin to understand the issues surrounding HIV transmission within Indian communities.